In a known atomizing system, water is introduced directly into the intake area of the fan, which is typically provided in the form of a fan with radial blades of the two-way type, designed to be operated in both directions of rotation in the execution of specified cooking cycles.
The aforesaid system provides for the supply of a flow of water at a predetermined rate to a position near the intake area of the fan, in such a way that, owing to the speed of the air and/or of the steam drawn in by the fan, this flow of water entering the intake area is distributed fairly uniformly over the inner surfaces of the blades, which, rotating at high speed (typically 1000 to 3000 revolutions per minute with a power supply frequency of 50 Hz), are able to atomize the flow.
The heating of the cooking chamber facilitates the subsequent evaporation of the atomized flow produced by the impact of the water on the fan blades. In this context, a typical application provides for the use of electrical resistances in the form of heating cables extending in coaxial configurations with the fan so as to cover the length of the blades and promote the exchange of heat with the air which carries the atomized flow of water into the delivery area of the fan, thereby facilitating the generation of steam inside the cooking chamber. Other applications provide for the use of combustion gas/air heat exchangers.
In cooking ovens where a plurality of fans are present, with respective associated heating means, and are typically provided in vertical superimposition on one another, it is necessary to supply water to each fan at substantially the same flow rate, subject to any tolerance on the flow rate values considered to be acceptable, to provide uniform temperature conditions inside the cooking chamber. In known systems, in which each fan is associated with a respective and distinct supply conduit, a tolerance of +/−20% in the flow rate values of each conduit is usually considered acceptable.
In the evaporation process the latent heat of evaporation of the water is very high, and, since the atomized water evaporation process is substantially adiabatic, it causes a substantial reduction in the air temperature when it takes place; if there are non-uniformities in the water flows which are atomized in the fans, there will be outgoing air flows at different temperatures, although these are still considered acceptable within the limits of the aforesaid tolerance. The aforementioned known solution meets this requirement by providing each fan with a respective water supply conduit, separate and distinct from the other conduits, on which flow rate control elements are provided; said elements may comprise calibrated apertures or proportional valves for controlling the flow rate. All of these arrangements are intended to ensure that each fan is struck by the same flow of water, subject to the accepted tolerances, to provide a substantial uniformity of steam generation so as to ensure uniform cooking conditions for the food present in the cooking chamber. Evidently, as the number of fans in the cooking chamber increases (applications using as many as five fans are commonly found in ovens for public catering), the water distribution system to be provided becomes more complicated, both because of the number of components and their overall dimensions, resulting in an increase in the associated costs (partly due to the amount of equipment required), and because of the overall layout of the system, given that each supply conduit, with its corresponding flow rate control elements, must also be connected to a common external supply source.
The fundamental problem of the present invention is that of providing a cooking oven with a device for distributing water for steam production inside the cooking chamber whose structural and functional design is such that the limitations of the aforementioned prior art can be overcome.